This invention relates generally to the field of automatic swimming pool cleaners, and more particularly, to cleaners of the type for submerged and generally random travel along the floor and sidewalls of a swimming pool to dislodge and collect debris.
By way of background, a swimming pool normally includes a water filtration system for removing dirt and debris from the pool water. Such filtration systems typically include a circulation pump which is installed outside the swimming pool and a piping system for coupling the circulation pump to the swimming pool. The circulation pump draws water from the swimming pool for delivery through the piping system to a filter unit. One or more baskets are located in the piping system upstream from the filter unit to catch larger debris, such as leaves and the like; the filter unit functions to separate dirt and fine debris from the water. The water is then recirculated by the pump back to the swimming pool.
A conventional water filtration system is satisfactory for removing dirt and debris of a relatively small size that is suspended in the water, but it is not designed to remove larger debris. Such systems depend on the aforementioned baskets to prevent larger debris from reaching the filter. However, it is generally advisable to clean out such baskets regularly to avoid the possibility that they may become clogged, blocking the flow of water through the pipes and resulting in damage to the circulation pump. Moreover, a conventional water filtration system is not designed to remove silt and debris which tends to settle irrespective of size onto the floor and sidewalls of a swimming pool.
To address the foregoing problems, automatic swimming pool cleaners for cleaning the floor and sidewalls of a swimming pool are well known. One particular type of known automatic swimming pool cleaner is shown and described in U.S. Pat. Nos. 3,822,754; 3,936,899; 3,972,339; and 4,558,479. This type of cleaner has three wheels positioned in a skewed triangular arrangement on the outside of a housing, with the housing having a front nose set angularly with respect to the direction of cleaner movement. An open and generally vertically oriented suction mast defines a flow path through the housing, with a collection bag mounted at the upper end.
This type of cleaner operates on pressurized water that is supplied to the cleaner through a supply hose. The water is used in part to drive the blades of a turbine which, in turn, rotates two or more of the wheels, and in part to induce a flow of pool water upwardly through the suction mast and into the collection bag. A portion of the pressurized water is also supplied through a sweep hose jet to a sweep hose and through a thrust jet, both at the rear of the cleaner. A booster pump may be used to generate added water pressure for the cleaner, because the circulation pump normally used in most swimming pool filtration systems does not create sufficient water pressure for all of the above purposes.
In operation of this type of cleaner, the drive wheels and thrust jet propel the cleaner along the floor and sidewalls of the swimming pool. When the pool cleaner reaches an obstruction preventing further direct forward travel, the skewed drive wheels and angled front nose of the cleaner housing imparts a turning movement, causing the cleaner to turn and continue travel in a different direction. Alternatively, when the cleaner travels along the pool floor and reaches a smoothly curved region merging with a sidewall, the cleaner tends to travel through the curved region and crawl at least part way up the pool sidewall with suction-assisted wheel traction until the cleaner falls by gravity back to the floor of the pool. A ballast float mounted at the upper rear of the cleaner helps assure that the cleaner will land upright on the pool floor and resume travel in a forward direction. As the cleaner travels around the pool, it vacuums the larger debris up through the suction mast into the collection bag. At the same time, the whipping action of the sweep hose sweeps any silt and smaller debris into suspension so that it can be filtered out by the pool's filtration system.
While submerged pool cleaning devices of the foregoing type have performed in a generally satisfactory manner, certain shortcomings have been observed in available commercial equipment. For example, existing cleaners have been constructed on the premise that it is advantageous for all three wheels to be driven by the turbine. In order to accomplish this, however, the cleaner has used a drive train for the wheels which either has been partly exposed to potential jamming or damage from contact with pool debris, or has used internal belts that have not proved highly reliable. In addition, existing cleaners have not typically been capable in practice of climbing the sidewalls of a swimming pool as aggressively as desired. For example, instead of the cleaner turning when it reaches a relatively sharp transition between the pool floor and a sidewall, it would be desirable for the cleaner to continue its forward travel and climb the sidewall. Further, it would be desirable for the cleaner to climb the sidewall nearly all the way to the waterline.
Accordingly, a need exists for an improved automatic swimming pool cleaner of the type adapted for submerged travel over pool surfaces to collect and dislodge debris which is capable of more aggressive climbing of pool sidewalls and which has a more reliable drive train that is not as exposed to potential jamming or damage from contact with pool debris. The present invention fulfills these and other needs.